JPH1093219A - High-frequency integrated circuit and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the rud for the adjustment of a resonance frequency and to improve alignment of a dielectric resonator with a high-frequency transmission line by forming a recess on part of a board and embedding the resonator in the recess. SOLUTION: Elements 12, such as active elements (e.g. FETS), a resistance element and a passive element (e.g. a capacitor) are formed on a surface of a GaAs substrate 11. Two or more layers of multilayer interconnections 14, 15 are formed on the board 11 via an insulating layer 13. Then, a predetermined region close to a microwave transmission line on a surface of a high-frequency integrated circuit (MMIC) 10 is selectively etched to form a recess (pit). Thereafter, a dielectric which functions as a resonator is embedded in the pit by using, for example, a sol-gel method. It is heat-treated, as needed, to crystallize the dielectric. Thus, a dielectric resonator 18 is formed, so as to magnetic field couple a microwave transmission line 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-frequency integrated circuit having a built-in dielectric resonator and a method of manufacturing the same.

[0002]

2. Description of the Related Art A dielectric resonator made of ceramic having a large dielectric constant has been used in order to highly integrate a frequency processing circuit in a high frequency region such as a microwave or a millimeter wave. This is because the size of the dielectric resonator can be reduced as the relative dielectric constant increases, which contributes to downsizing of the high-frequency integrated circuit.

Conventionally, in a high-frequency integrated circuit using a dielectric resonator, in order to obtain a desired resonance frequency, a sintered dielectric is machined to produce, for example, a columnar dielectric resonator. The body resonator is connected to MMIC (Microwave).
Monolithic Integrated Ci
rcuit) It is used by bonding to a high-frequency transmission line on the surface so as to be magnetically coupled.

However, the processing accuracy required to obtain a desired resonance frequency is ± 0.1%. Therefore, for example, when manufacturing a cylindrical dielectric resonator having a height of 1 mm and a diameter of 1 mm, the processing accuracy needs to be 1 mm ± 1 μm.
However, the size varies in machining,
There is a problem that the resonance frequency varies from element to element. Therefore, it is necessary to adjust the frequency for each machined element. There is also a problem that it is difficult to align the dielectric resonator and the high-frequency transmission line. In addition, MMIC
Flip chip mounting was not possible because the dielectric resonator adhered to the surface protruded.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-frequency integrated circuit which does not require adjustment of a resonance frequency, has good alignment between a dielectric resonator and a high-frequency transmission line, and can be flip-chip mounted. It is an object of the present invention to provide a circuit and a method for easily manufacturing such a high-frequency integrated circuit.

[0006]

According to the present invention, there is provided a high frequency integrated circuit comprising: a substrate having a high frequency transmission line; and a dielectric resonator provided on the surface of the substrate so as to be magnetically coupled to the high frequency transmission line. In the circuit, a concave portion is formed in a part of the substrate, and a dielectric resonator is embedded in the concave portion.

According to the method of manufacturing a high-frequency integrated circuit of the present invention, a step of forming a high-frequency integrated circuit on a substrate, a step of selectively etching a substrate surface to form a concave portion, and a step of forming a concave portion on the substrate surface by resonance. And embedding a dielectric functioning as a container.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The high-frequency integrated circuit to which the present invention is applied is 10 GHz
It is preferably used at the above high frequency.

In order to manufacture the high frequency integrated circuit (MMIC) of the present invention, the following method is used. First, elements such as an active element (for example, a transistor), a resistance element, and a passive element (for example, a capacitor) are formed on the surface of a semiconductor substrate such as GaAs or Si by a normal method.
On the substrate, a multilayer wiring of two or more layers is formed via an insulating layer, and a microwave transmission line or the like is provided on the surface of the insulating layer.
Next, a predetermined area near the microwave transmission line on the surface of the MMIC is selectively etched to form a concave portion (pit). The shape of the pit is not particularly limited. The pits can be formed by, for example, a method such as reactive ion etching (RIE). Next, a dielectric functioning as a resonator is buried inside the pit by using, for example, a sol-gel method. Heat treatment is performed as needed to monocrystallize the dielectric. Thus, the dielectric resonator is formed so as to be magnetically coupled to the microwave transmission line. Note that the microwave transmission line may be formed after forming the dielectric resonator inside the pit.

In the present invention, as a dielectric material constituting the dielectric resonator, Ba (Mg _1/3 Ta _2/3 ) O ₃ ,
Ba (Zn _1/3 Ta _2/3 ) O ₃ , (Ba, Sr) (Ga
_1/3 Ta _2/3 ) O ₃ , Ba (Mg _1/3 Nb _2/3 ) O ₃ ,
Ba (Zn _1/3 Nb _2/3 ) O ₃ , (Ba, Sr) (Ga
It is preferable to use at least one selected from the group consisting of _1/3 Nb _2/3 ) O ₃ and solid solutions thereof. Also, if the coefficient of thermal expansion between the dielectric material and the constituent material of the MMIC increases, the dielectric may be detached from the MMIC,
Although there is a possibility that an external force is applied to the MMIC to deteriorate its characteristics, these dielectric materials have a thermal expansion coefficient substantially equal to that of the constituent materials of the MMIC such as GaAs. It becomes possible. In particular, when the dielectric is made single crystal, this effect is remarkably exhibited.
Further, by making the dielectric single crystal, the dielectric loss at a temperature of 150 ° C. or higher or −50 ° C. or lower can be reduced.

In the present invention, the resonance frequency is determined by the size of the dielectric buried in the pit, that is, the size of the pit to be formed. The size of the pit can be accurately formed by using a method such as RIE. Therefore, the variation in the resonance frequency of the manufactured resonator is small, and the frequency correction is unnecessary, so that the manufacturing efficiency is improved. If a method such as RIE is used, the positioning accuracy of the dielectric resonator with respect to the high-frequency transmission line is good. Furthermore, since the surface of the MMIC is flattened by embedding the dielectric resonator inside the pit, flip-chip mounting becomes possible.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a high-frequency band wireless communication device including a high-frequency integrated circuit of the present invention. This high-frequency band wireless communication device is a transmission / reception module.

In FIG. 1, a transmitting antenna 2 and a receiving antenna 3 are formed on an alumina substrate 1. A semiconductor chip 4 having a device formed on a GaAs substrate is mounted on an alumina substrate 1, and a transmitting antenna 2
And the receiving antenna 3 and the bonding wire 5. The alumina substrate 1 is housed in a package 6 provided with input / output terminals 7. As a material of the package 6, Kovar, 42 alloy, Cu, Al, or the like is used. Although not shown, the package 6
An opening for transmission and reception is provided at the upper part of the transmission antenna 2 so that the transmission antenna 2 and the reception antenna 3 can transmit and receive radio waves.

FIG. 2 is a circuit block diagram of the high-frequency band wireless communication apparatus shown in FIG. As shown in FIG.
Includes a LNA (low noise amplifier) as a receiving means and a direct demodulation circuit connected to the LNA, a transmitting means as a direct modulation circuit, an OSC (oscillator) for controlling the direct modulation circuit, and a PA (power) connected to the direct modulation circuit. Amplifiers) are incorporated. The signal received by the receiving antenna 3 is output as a baseband signal via the LNA and the direct demodulation circuit. On the other hand, the baseband signal is directly input to the modulation circuit, and further transmitted from the transmission antenna 2 via the PA. Control signals for controlling the direct demodulation circuit, the direct modulation circuit, and the OSC are input from outside the semiconductor chip 4. The above-described baseband signal and control signal are input / output via the input / output terminal 7 shown in FIG. A dielectric resonator is used as a component of the OSC.

FIG. 3 shows an example of a direct modulation circuit. This direct modulation circuit performs AM modulation, and uses a modulation FET.
The switching method using is adopted. The input baseband signal is modulated by the modulation FET,
The signal is output to the PA through the matching circuit, and further transmitted from the transmitting antenna 2. At this time, the modulation signal is being input from the OSC to the resistor.

FIG. 4 shows an example of a direct demodulation circuit. LNA
Is taken out through a detuning circuit, demodulated and detected by a diode, and output as a baseband signal. Although the use of the detuning circuit as shown in FIG. 4 is to increase the selectivity of the signal, a normal tuning circuit may be used. Further, a nonlinear amplifier may be used instead of the diode.

FIG. 5 is an exploded perspective view of another high-frequency band wireless communication apparatus according to the present invention, and FIG. 6 is a circuit block diagram thereof.
The device of FIG. 5 differs from the device of FIG. 1 in that two semiconductor chips 4 ₁ and 4 ₂ are used.
As shown in FIGS. 5 and 6, the semiconductor chip 4 ₂ L
NA is, transmission and reception means other than LNA is incorporated in the semiconductor chip 4 _1. Since the LNA is a part that directly receives a signal from the receiving antenna 3, it has a large effect on other circuits such as interference. On the other hand, when only the LNA is incorporated into a single semiconductor chip as shown in FIGS.
The influence of the NA on other circuits can be suppressed.

FIG. 7 shows an equivalent circuit diagram of an MMIC having a built-in dielectric resonator. This oscillator uses FE as an oscillation element.
It has T. To the source S of the FET, a stub 21 for generating a negative resistance having a short-circuit at the tip and also serving as a ground is connected. The resonance circuit 22 is connected to the gate G.
The matching circuit 23 is connected to the drain D, and an output is taken out. In the gate-drain bias circuit of the FET, a short stub composed of a quarter wavelength line and a bypass capacitor is used. Further, a dielectric resonator is provided so as to be magnetically coupled to the microwave transmission line.

With this configuration, since the source S of the FET is grounded, a feedback circuit including a resonator is inserted between the source S and the gate G. Since the resonator exhibits band rejection characteristics, feedback is provided only at the resonance frequency and stable oscillation can be obtained by appropriately setting the distance between the resonator and the FET.

FIGS. 8A and 8B show the device structure of the MMIC 10 shown in FIG. FIG. 8A is a perspective view with a part cut away, and FIG. 8B is a plan view. In FIG. 8, elements 12 such as an active element (for example, FET), a resistance element, and a passive element (for example, capacitor) are formed on a surface of a GaAs substrate 11 of 5 mm square. On the substrate 11, a multilayer wiring 1 of two or more layers via an insulating layer 13.
4 and 15 are formed. The uppermost layer of this multilayer wiring is the ground conductor layer 15. On the surface of the insulating layer 13,
A spiral inductor 16, a microwave transmission line 17, an antenna, and the like are formed. Then, the dielectric resonator 18 is coupled to the microwave transmission line 17 so as to be magnetically coupled.
Are formed. As a material of the insulating layer, polyimide, an organic resin such as BCB (benzocyclobutene), or SiO ₂ can be used. When an organic resin is used, a thick insulating layer having low dielectric constant and low loss can be formed. The materials constituting the multilayer wiring include Al, Au, C
u or the like can be used.

The above-described dielectric resonator 18 was formed as follows. First, after a resist having a predetermined pattern is formed, a 1.3 m diameter is formed on the surface of the MMIC 10 by RIE.
A columnar pit having a depth of 0.6 mm and a depth of 0.6 mm was formed. Next, using a sol-gel method, Ba (Mg _1/3 Ta
_2/3 ) An O ₃ dielectric was formed and crystallized by laser annealing.

The obtained MMIC has a design oscillation frequency of 6
An oscillation frequency of 60.5 GHz was obtained with respect to 0 GHz, and the error was as high as 1% or less. As shown in FIG. 9, the planar shape of the pit may be quadrangular and the prismatic dielectric resonator 18 may be embedded.

Further, as shown in FIG.
After embedding the dielectric resonator 18 on the surface of the substrate 10, the microwave transmission line 17 may be formed on the dielectric resonator 18.
According to such a method, the positioning accuracy between the dielectric resonator 18 and the microwave transmission line 17 can be further improved.

[0024]

As described above in detail, according to the present invention, the adjustment of the resonance frequency is unnecessary, the alignment between the dielectric resonator and the high-frequency transmission line is excellent, and the flip-chip mounting is possible. A high-frequency integrated circuit and a method for easily manufacturing such a high-frequency integrated circuit can be provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an example of a high-frequency band wireless communication device including a high-frequency integrated circuit of the present invention.

FIG. 2 is a circuit block diagram of the high-frequency band wireless communication device of FIG. 1;

FIG. 3 is a circuit block diagram illustrating an example of a direct modulation circuit.

FIG. 4 is a circuit block diagram illustrating an example of a direct demodulation circuit.

FIG. 5 is an exploded perspective view showing another example of the high-frequency band wireless communication device including the high-frequency integrated circuit of the present invention.

FIG. 6 is a circuit block diagram of the high-frequency band wireless communication device of FIG. 5;

FIG. 7 shows an MMIC incorporating a dielectric resonator according to the present invention.
FIG.

FIG. 8 shows an MMIC incorporating a dielectric resonator according to the present invention.
The perspective view and top view which show and fracture | rupture a part of it.

FIG. 9 is a perspective view showing another configuration example of the dielectric resonator according to the present invention.

FIG. 10 is a perspective view showing still another configuration example of the dielectric resonator according to the present invention.

[Explanation of symbols]

1 ... alumina substrate 2 ... transmission antenna 3 ... receiving antenna 4,4 _1, 4 ₂ ... semiconductor chip 5 ... bonding wire 6 ... package 7 ... output terminals 10 ... MMIC 11 ... GaAs substrate 12 ... device 13 ... insulating layer 14 ... Multilayer wiring 15 Ground conductor layer 16 Spiral inductor 17 Microwave transmission line 18 Dielectric resonator 21 Stub 22 Resonant circuit 23 Matching circuit

Claims (3)

[Claims] 1. A high-frequency integrated circuit comprising: a substrate having a high-frequency transmission line; and a dielectric resonator provided on a surface of the substrate so as to be magnetically coupled to the high-frequency transmission line.
A high frequency integrated circuit, wherein a concave portion is formed in a part of the substrate, and a dielectric resonator is embedded in the concave portion. 2. The dielectric material is Ba (Mg _1/3 Ta _2/3 ) O.
₃ , Ba (Zn _1/3 Ta _2/3 ) O ₃ , (Ba, Sr)
(Ga _1/3 Ta _2/3 ) O ₃ , Ba (Mg _1/3 Nb _2/3 )
O ₃ , Ba (Zn _1/3 Nb _2/3 ) O ₃ , (Ba, Sr)
2. The high-frequency integrated circuit according to claim 1, wherein the high-frequency integrated circuit is at least one selected from the group consisting of (Ga _1/3 Nb _2/3 ) O ₃ and a solid solution thereof. 3. A step of forming a high-frequency integrated circuit on a substrate, a step of selectively etching a surface of the substrate to form a recess, and embedding a dielectric functioning as a resonator in the recess formed on the substrate surface. And a method for manufacturing a high-frequency integrated circuit.